﻿var net=new Object();
//	编写构造函数
net.AjaxRequest=function(url,onload,onerror,method,params){
	this.req=null;
	this.onload=onload;
	this.onerror=(onerror)?onerror:this.defaultError;
	this.loadDate(url,method,params);	
}
//  编写用于初始化XMLHttpRequest对象并指定处理函数，最后发送HTTP请求的方法
net.AjaxRequest.prototype.loadDate=function(url,method,params){
	if(!method){
		method="GET";
	}
	if(window.XMLHttpRequest){
		this.req=new XMLHttpRequest();
	}else if(window.ActiveXObject){
		this.req=new ActiveXObject("Microsoft.XMLHTTP");
	}
	if(this.req){
		try{
			var loader=this;
			this.req.onreadystatechange=function(){
				net.AjaxRequest.onReadyState.call(loader);
			}
			this.req.open(method,url,true);
			if(method="POST"){
				this.req.setRequestHeader("Content-Type","application/x-www-form-urlencoded");
			}
			this.req.send(params);
		}catch(err){
			this.onerror.call(this);
		}
	}
}

//  重构回调函数
net.AjaxRequest.onReadyState=function(){
	var req=this.req;
	var ready=req.readyState;
	if(ready==4){
		if(req.status==200){
			this.onload.call(this);
		}else{
			this.onerror.call(this);
		}
	}
}

//  重构默认的错误处理函数
net.AjaxRequest.prototype.defaultError=function(){
	alert("error fetching data!"
			+"\n\nreadyState:"+this.req.readyState
			+"\nstatus:"+this.req.status
			+"\nheaders:"+this.req.getAllResponseHeaders());
}









